Ok so while cleanin my G19 today i notice a set of 10 digits on the barrel that i had never noticed on my other 3 glocks G21sf, G29, n G27. So when i go to clean the slide i noticed another set of 10 digits again, so then i moved on to the frame and to my surprise another 10 digits. so i go n pull out n chek my other glocks n only one that doesnt have em is the G27. The G29 n G21 have em only on the frame, n not on the barrel or slide. Im goin to contact Glock durin the week to see what they have to say. but any 411 on this subject would be helpful Thanx!!